Robert Plomin, in "Blueprint,"
compared popular assumptions about the heritability of various traits to the best we can do for scientific evidence for each trait. In every case but one, traits were much more heritable than people liked to think. The exception was breast cancer, whose heritability is overestimated 5x.
Table 2 How much are these traits influenced by genetics? [%] The first column of results shows the average opinions of 5,000 young adults in the UK. The second column shows results from genetic research.
Eye colour 77 95
Height 67 80
Breast cancer 53 10
Schizophrenia 43 50
Autism 42 70
General Intelligence 41 50
Weight 40 70
Reading disability 38 60
Personality 38 40
Spatial ability 33 70
Remembering faces 31 60
Stomach ulcers 29 70
School achievement 29 60
Verbal ability 27 60
Trait or skill? I can see eye color (NPI)or height ,but how does one measure whether verbal ability or school achievement are because of genetics or being taught ?
ReplyDeleteDang- stormy night -power keeps going out.
One would presume that they had access to people who had multiple generations tested for whatever trait they were looking at, and compared incidence to what you would expect from random mutation.
ReplyDeleteInteresting that, after breast cancer, personality was the least genetic affected factor. That's the one that says who your are more than any of the others, by far. Of course, I think Raven's critique fits that category well- how do you evaluate that as genetic or not?
how does one measure whether verbal ability or school achievement are because of genetics or being taught?
ReplyDeleteaccess to people who had multiple generations tested for whatever trait they were looking at, and compared incidence to what you would expect from random mutation.
How would they sort genetics from nurture/culture over those generations? How would they estimate expectation of random mutation wrt "verbal ability?" We have a hard enough time sorting that out on genetics with homo sapiens vs neanderthal vs denisovan.
Eric Hines
@ raven. That is actual one of the more robust findings that nurture doesn't contribute that much. Twin studies, adoption studies, sibling and half-sibling similarity. Many replications.
ReplyDeleteThis gets obscured for a couple of related reasons. People don't want it to be true, because then it's not easily copyable Jewish mothers or Tiger moms, but that Jews and Northeast Asians have better cognitive skills than whites and then...oh dear. Can't have that. Second, because they don't want it to be true, most social science researchers do not even consider the possibility of genetics in their result. Every difference is assumed to be somehow environmental. You'd swear that no researcher in the field has any siblings or more than one child, they are so dense about it.
There have been a hundred nominations for environmental factors: Number of words spoke to the child, number of books in the home, number of computers in the school, age of textbooks in the school, attendance at pre-K, nutrition, class size, local crime rate, family income, education of parents, everything you can think of. When you isolate each of these things to compare apples to apples, they turn out to be associations only. Bright parents read to their children more, explain things to them, get them into better school districts...but if an equivalent groups of children who are adopted out into less-supportive environments are measured for verbal ability as adults, they have the same IQ as the ones in the good environments. Sad but true, for one like me who put a lot of time and money into the education of my children.
By age 35, the vocabularies of those with the same IQ who did and did not go to college equal out. Even at 22 it's not huge.
It's interesting that IQ is only 50% heritable, but school achievement and verbal ability are 60%.
ReplyDeleteAnyway, with those percentages, all the time & money you put into it probably paid off in the other 50/40% areas.
I also think for research purposes terms like personality and verbal ability are probably more narrowly defined than they are in general use.
For those who don't think that such things have been or even could be evidenced to the point of near-proof, I have abundant links and recommendations. The objections raised here were good ones, decades ago when they were first raised. Researchers have taken them into account since then.
ReplyDeleteAchievement is only partly native ability (IQ or running speed or whatever). Stick-to-it-iveness is a big component too, and if that's partly genetic...
ReplyDelete@ james. Yes, exactly. There are many other qualities that go into success, by usual definitions. IQ ain't everything by a long shot. But that doesn't mean that those other qualities are the result of nurture, either.
ReplyDeleteAVI, I'm curious, how much (if at all) do you believe nurture plays a role in any of this?
ReplyDeleteIF this is all correct, then wouldn't you expect hereditary aristocracy to be the most effective form of government?...also, descent of professions from parent to child. If an individual has the right mix of intelligence, personality, spatial ability, etc to be a good naval officer, for example, then wouldn't it be a good bet that his son or daughter would also do well in that role?
ReplyDeleteThe two biggest advantages I have had in life, were being taught to read well, and early, and being taught to work hard, and do my best. These have managed ,somehow, to overcome all the obstacles I have placed in my way. Loner, drop out, street kid, all succumbed to the Key's of Learning- literacy and hard work.
ReplyDeleteMay God bless my Parents.
David Foster's point is excellent, and has been known as a problem since Socrates, who raised the point in asking whether any sort of excellence was or was not teachable.
ReplyDeleteFrom the Protagoras, who was challenging him on the point:
"But why then do the sons of good fathers often turn out ill? There is nothing very wonderful in this; for, as I have been saying, the existence of a state implies that virtue is not any man's private possession. If so-and nothing can be truer-then I will further ask you to imagine, as an illustration, some other pursuit or branch of knowledge which may be assumed equally to be the condition of the existence of a state. Suppose that there could be no state unless we were all flute-players, as far as each had the capacity, and everybody was freely teaching everybody the art, both in private and public, and reproving the bad player as freely and openly as every man now teaches justice and the laws, not concealing them as he would conceal the other arts, but imparting them-for all of us have a mutual interest in the justice and virtue of one another, and this is the reason why every one is so ready to teach justice and the laws;-suppose, I say, that there were the same readiness and liberality among us in teaching one another flute-playing, do you imagine, Socrates, that the sons of good flute players would be more likely to be good than the sons of bad ones? I think not. Would not their sons grow up to be distinguished or undistinguished according to their own natural capacities as flute-players, and the son of a good player would often turn out to be a bad one, and the son of a bad player to be a good one, all flute-players would be good enough in comparison of those who were ignorant and unacquainted with the art of flute-playing? In like manner I would have you consider that he who appears to you to be the worst of those who have been brought up in laws and humanities, would appear to be a just man and a master of justice if he were to be compared with men who had no education, or courts of justice, or laws, or any restraints upon them which compelled them to practise virtue-with the savages, for example, whom the poet Pherecrates exhibited on the stage at the last year's Lenaean festival. If you were living among men such as the man-haters in his Chorus, you would be only too glad to meet with Eurybates and Phrynondas, and you would sorrowfully long to revisit the rascality of this part of the world. you, Socrates, are discontented, and why? Because all men are teachers of virtue, each one according to his ability; and you say, Where are the teachers? You might as well ask, Who teaches Greek? For of that too there will not be any teachers found. Or you might ask, Who is to teach the sons of our artisans this same art which they have learned of their fathers? He and his fellow-workmen have taught them to the best of their ability,-but who will carry them further in their arts?"
And yet, as Socrates demonstrates by the end, Protagoras thinks that excellence is not knowledge, but can be taught; Socrates thinks it is knowledge, but cannot be taught.
There are great points being raised in that excerpt. Who teaches Greek? Well, we have English teachers and classes these days; but in those days people somehow learned the whole language -- down to composition and public speaking -- without them. Protagoras was an early teacher of rhetoric; Socrates claimed not to teach anything.
Yet he did, of course. We've been learning from him for two thousand years. That means we can learn something; something you won't learn if you don't read Plato. So there's some role for nurture.
But somehow still great men give bad sons, and yet also 'teaching nothing' seems to work best.
The two biggest advantages I have had in life, were being taught to read well, and early, and being taught to work hard, and do my best.
ReplyDeleteI think my biggest advantages have both been family. But one is nurture, and one nature. I must have gotten some good genes somewhere, since I'm reasonably smart and physically strong. But I also was raised by parents who loved me as well as trained me. I think that's got to count for something, but maybe -- I think this is AVI's point -- they were the kind of people who were genetically inclined to love as well as train.
David Foster said...
ReplyDeleteIF this is all correct, then wouldn't you expect hereditary aristocracy to be the most effective form of government?...also, descent of professions from parent to child. If an individual has the right mix of intelligence, personality, spatial ability, etc to be a good naval officer, for example, then wouldn't it be a good bet that his son or daughter would also do well in that role?
A shorter answer than Grim's - Note that even AVI is not saying that these traits are 100% heritable, or that the distribution is even among the offspring. You don't have to look too far right now to find a pretty shining example (though Dad isn't looking like a great prize, either). It wouldn't be a bad bet that the offspring of an excellent Naval officer or government administrator might follow in the parent's footsteps but the proof will be in the doing. It's not a reason to create a hereditary caste of executives and administrators.
Tom - It varies by trait. We do not know the answer for many traits and I will rejoice to find that my parenting efforts were not superfluous. My overall view is that there is value for nurture more at the extremes. The exceptionally skilled gain value from good coaching. Those at the mouth of hell can be rescued through great effort.
ReplyDeleteAs for hereditary aristocracy, evolution accomplishes some of that, as the skilled feed more children through childhood, and the type of jobs available in an area tend to be similar in the next generation. This is now changing, and I don't know what will result. At the highest levels, it is often a combination of abilities that make a good leader, and whether one's spouse, allies, and associates have complementary skills to the 50% you inherited from your father is fairly random. There are too many variables for it to be more than a partial advantage. As others have noted, observation of what a person can actually do is more reliable.
Things that look like training are often just genetic, but we have convinced ourselves of the story - complete with anecdotes from childhood! - that we were taught these things by our parents.
Ability may be pretty baked in. Success is less so. It has so much to do with good habits and virtues, and I see no evidence that those are heritable.
ReplyDeleteInteresting that, after breast cancer, personality was the least genetic affected factor.
ReplyDeleteThat's because how the human mind thinks, as an avatar persona, is primarily affected by the location of the moon when one is taking the First Breath.
IF this is all correct, then wouldn't you expect hereditary aristocracy to be the most effective form of government?
ReplyDeleteNo, because aristocracy purports to breed virtues into humans, which inteferes with the celestial decree and fate of Heaven and Earth.
They can perhaps breed qualities or talents into human blood lines, or even IQ, but actual virtue or benevolent rulership or wise rulership, those are not qualities that are allowed to be dictated solely by genetics.
There's always been a blue blood aristocratic or Asian belief that criminals produce criminals and noble smart elites produce noble smart elites. But much of that is due to tradition and environment activating the epigenetic markers dormant in DNA.
Meaning, if a son of a ruler is exposed to the exact same things in the exact same sequence as his father, grandfather, and so forth, then he has a high chance of activating the epigenetic markers that led to his ancestors ruling. But this is like rags to riches back to rags story. The environment changes entirely due to the ruling power of his ancestors. He didn't grow up as a steppe child o at the bottom, he now grows up near the top of the social status. Completely different environment which activates different parts of the DNA and epigenetic sequences.
For those that don't follow the research, this is a basic kind of ancestral memory of skills and events carried within the DNA and blood lines.
A native case is Lyndon B Johnson's successful prediction that he would get black nigs voting Demoncrat for an entire century, after his welfare policies collapsed the middle class families. Black families were already imprinted with the broken family issue of the slave days, but that was turning around as American middle class values changed the DNA itself. Which was promptly noticed and then reversed by the ruling elites. Some of them do know how to breed rulers and by extension slaves.
Socrates thinks it is knowledge, but cannot be taught.
Another way of saying it is known by fate but cannot be taught because it would require dictating a person's birth time and fate. The Greeks believed in many things that the moderns could not, and as a result they do not truly understand the ancient philosophies either. Case in point, Oracle of Delphi (snake fumes). Many individuals, including Alexander the Great, used them. And not as a joke either.
Socrates had penetrated to the esoteric inner teachings. He understood that in order to teach, he had to learn, and as a result of his human foolishness, there's too many things for him to learn before he could teach. Thus in the process of learning what he could not teach, he gave a good example for others to learn from. That is teach/learning, where true teaching requires the teacher to learn just as much if not more than the student. THis is a concept foreign to modern Westerners for the most part. Top down hierarchy systems tend to be blind to certain quality of life issues.
If an individual has the right mix of intelligence, personality, spatial ability, etc to be a good naval officer, for example, then wouldn't it be a good bet that his son or daughter would also do well in that role?
That actually seems to be more common, such as military families. Nobility was originally a martial craft, so it made sense that the sons and daughters would also be warriors and thus nobles. That changed when nobility were no longer required to be the best warriors.